Throughout the world, many people clean fabrics by hand washing or machine-assisted hand washing with compositions containing soap and/or detergent. Machine-assisted hand washing of fabrics involves the use of a manual or semi-automatic wash machine with completion of the wash process by hand washing.
In many geographies where hand washing is prevalent, the water hardness of calcium and magnesium ions can be as high as 25 grains/gal as equivalent CaCO3, or higher. Under such high hardness conditions, the builder capacity of the laundry detergent to sequester all the hardness can be exhausted. In this condition, conventional surfactant systems lose their cleaning performance capability, or at least their cleaning performance is substantially less than in conditions where the builder system can sequester substantially all hardness.
Furthermore, hand-wash laundry detergent compositions are preferably formulated to provide good cleaning, including adequate cleaning on greasy and body soil stains, while remaining mild to the skin of the hands. In general, there remains a need to improve the cleaning of these soils while maintaining good mildness on the hands.
Effective hand wash detergent compositions comprise anionic surfactants, particularly alkylbenzene sulfonate and alkyl sulfate surfactants. It has also been found beneficial for the appearance and cleaning of cotton fabrics for hand wash laundry detergents to contain an amount of a cellulase enzyme sufficient to improve the appearance and cleaning of such fabrics, particularly after multiple cleaning cycles. However, it is known that the presence of anionic surfactants can inhibit the activity of the cellulase enzymes, thereby reducing the effectiveness of the cellulase to deliver the appearance and cleaning improvements.
European Patent Application 0,051,986 (The Procter & Gamble Company) discloses a granular detergent composition containing mixtures of anionic surfactant, preferably alkylbenzene sulfonate and alkyl sulfate, and mixtures thereof with soap, an alkoxylated nonionic surfactant, and a water soluble cationic surfactants.
It is an object of the subject invention to provide a detergent laundry composition which provides superior cleaning performance in hand wash or machine-assisted hand wash laundry operations.
Another object of the present invention is to provide a surfactant system for a detergent composition which can maintain good cleaning performance under high hardness conditions even after the builder capacity of the laundry detergent composition to sequester the hardness in wash water has been stressed or exhausted.
It is a further object to provide a hand wash detergent composition which provides improved cleaning performance on greasy and body soils without diminishing the mildness of the product on the hands.
It is yet another object of the present invention to provide a synergistic surfactant system containing alkylbenzene sulfonate surfactant which minimizes interferance with the activity of cellulase enzymes toward cellulosic fabric substrate.
It is another object to provide the above-mentioned benefits while maintaining good sudsing of the detergent composition during hand washing.